Collaborative Research: Structure and Evolution of M31's Stellar Halo from a Large-Scale Spectroscopic Survey

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PROPOSAL NO: AST-0307931PI: Michael RichINSTITUTION: University of California, Los Angeles================================================================This collaborative project is led by Puragra Guhathakurta of UCSC (AST-0307966), and includes Michael Rich of UCLA (AST-0307931), Steven Majewski of University of Virginia (AST-0307842) and Kathryn Johnston of Wesleyan University (AST-0307846).This team of collaborators will improve our understanding of the nature and origin of the halo of M31 by carrying out a large-scale spectroscopic survey that will yield both stellar radial velocities and metallicities. The larger sample will allow them to explore the halo/outer disk stellar population over a wide range of galactocentric distances by determining the mean metallicity distribution function, the outer rotation curve, and the velocity dispersion of the halo. Their study will focus on results for stars in the discrete streams of material in the halo that have been discovered recently from wide field imaging surveys. Ultimately, their sample should allow them to assess the extent to which the disruption of satellite galaxies accreted by M31 has contributed to the formation of the halo population. All of the collaborators involve undergraduate and graduate students in their research efforts. They expect to give public lectures and to speak in K-12 classrooms about their research and to make the results of their work accessible to the public. They also plan to purchase a narrow band filter for work on the Ca infrared triplet, which will be made available to all users of the Keck telescopes.